Metal Halide to LED Conversion Calculator
This Metal Halide (MH) to LED Conversion Calculator will assist you in determining the appropriate LED wattage that a new LED luminaire will need to achieve the equivalent lumens to replace an existing Metal Halide luminaire. The calculator is quite effective for determining replacements where the old fixtures will be replaced on a one-for-one basis from Metal Halide to LED. Equivalent lumens is based on the average lumen output of the currently installed MH lamp in an existing luminaire. Explanations of all terms are listed below the calculator. If you have questions, you can always ask an Access Fixtures Lighting Specialist.
|Metal Halide (MH) Lamp Watts|
|Lamp Mean Lumens|
|Mean Luminaire Lumens|
|LED Fixture Lumens Per Watts|
|LED Mean Luminaire Equivalent|
|Equivalent with Maintenance Factor (MF)|
|LED Energy Savings|
MH to LED Conversion Calculator Lighting Terms
Metal Halide (MH) Lamp Watts
What is the wattage of the current Metal Halide light bulb you are using?
MH light fixtures have a lamp (light bulb) and a ballast. The ballast converts the electrical voltage supplied to power that ignites and keeps the lamp on. System watts is the combined wattage of the lamp and the electricity used by the ballast.
Lamp Mean Lumens
Metal Halide lamps, like all lamps, suffer lumen deprecations. That means when the MH lamp is new, the lamp emits more light than when the lamp is 40% through its average life. Mean lumens is the average lumens emitted by the lamp over the life of the lamp.
MH luminaires (light fixtures), like most legacy luminaires, have features that enhance the light emitted from the lamp and somewhat direct the light emitted from the lamp. That doesn’t mean that all the light emitted from the lamp gets out of the luminaire. Some light is lost due to the inherent inefficiency of the luminaire housing. Some light is lost due to the non-transparent elements of the luminaire housing. Some light is lost when the light passes through the lens. The default for this is 80%. If you prefer to be more precise, speak with an Access Fixtures Lighting Specialist about the estimated luminaire efficacy of the specific luminaire you are replacing.
Mean Luminaire Lumens
This is the calculation that determines the average light emitted by the MH luminaire. It is mean MH lamp lumens times the efficacy of the luminaire.
LED Fixture Lumens Per Watt
If you are purchasing a new LED luminaire, LED Fixture Lumens per Watt information should be provided in the specifications of the new LED light luminaire that you are considering purchasing. Be wary of the information provided. The LED wattage used for this should be system watts. System watts is the wattage of the LED based on the mA provided by the LED driver and the wattage used by the LED driver. There is also a difference between LED lumens and luminaire lumens. LED lumens is the lumens per watt of the LEDs. Just like legacy luminaires, the lamp lumens are not the same as the luminaire lumens. Luminaire lumens is the lumens per watt emitted by the luminaire. What is the information that you want for LED Fixture Lumens per Watt? It is LED Luminaire Lumens divided by LED System Watts. Again, this should be provided, but be sure that you are getting the correct information.
If you are looking for a LED retrofit lamp, it starts to get more complex. The LED retrofit will be affected by the luminaire efficacy, and the luminaire efficacy will most likely be lower for the LED retrofit than it is for a MH lamp. This is due to the different optics of the LED retrofit and how LEDs lose efficacy when the light is transmitted through glass. Be sure to speak with an Access Fixtures lighting specialist to determine the best solution.
LED Mean Luminaire Equivalent
This is calculated by dividing the HID Mean Luminaire Lumens by the LED Luminaire Lumens per Watt. It provides the mean. equivalent wattage before adjusting for the Maintenance Factor.
Equivalent with Maintenance Factor (MF)
LED luminaires have lumen depreciation too. , so there is a calculation required similar to HID Mean Lamp Lumens. LED luminaires have an L70 rating such as L70 @ 100,000 Hours. That means that over 100,000 hours of use the lumens emitted will decline to 70% of the original light emitted by the LED luminaire. While that is la long time, time passes. Enough light when new may not or will not be enough light later. For example, if a tennis court design delivers 30 footcandles (fc) and 30fc is required for that level of tennis, there will not be enough light to play tennis at 25fc. Access Fixtures lighting engineers recommend that a MF of 20%. be added to maintain sufficient lumens for the task.
LED Energy Savings
This is a comparison of the MH system watts used as compared to the LED system watts.
MH to LED Conversion Calculator Disclaimer
This calculator is provided as a tool to help electricians, facility managers and others to get a fairly accurate estimate of the LED wattage required to provide an equal amount of lumens. When selecting a new LED fixture or retrofit, there are other factors to take into consideration.
For example, optics including beam spread determine the pattern and how wide the light is distributed. Speak with an Access Fixtures lighting specialist about your project to get the answers you need from a professional.
Access Fixtures assumes no responsibility for information provided or action taken based on use of this MH to LED Conversion Calculator.
Conversion from Metal Halide to LED – Next Steps
What are the next steps required to convert from MH to LED? You could simply guess at what the best LED light fixture is for your application based on the LED light fixture providing similar lumens, or you could speak with an expert. Call 800.468.9925 and talk to an Access Fixtures lighting specialist or submit the form below.
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